1. Field of the Invention
This invention relates generally to wireless devices and voice over Internet Protocol (VoIP) technologies. More particularly, it relates to ENUM services.
2. Background of the Related Art
Electronic numbering (ENUM) services have been called implementation of a ‘phone number for life’. Just like a social security number follows a person for life, ENUM envisions use of a single simple telephone number to access a person over any applicable medium (e.g., telephone network, FAX, Internet, etc.) Thus, as currently envisioned, electronic numbering (ENUM) services give subscribers a single telephone number that can be used to access any of their communications services or devices via an Internet Protocol (IP) network, e.g., voice, fax, email, short message service (SMS), etc.
For use in the Internet world, ENUM is a protocol for mapping a telephone number to a Uniform Resource Identifier (URI) which can be used to contact a resource associated with that number. ENUM in this scenario therefore gives access to a wide range of a person's (communication) identifiers by looking up a specific domain associated with that person's telephone number.
In operation, an ENUM service receives a dialed (or addressed) phone number, and uses a mathematical formula and lookup table(s) to resolve it to an Internet Uniform Resource Identifier (URI) for the subscriber's ENUM Naming Authority Pointer (NAPTR) record, a repository of communications access information. The service then routes the call or communication to a service provider based on the type of request, e.g., voice, fax, email, etc., and any preferences established by the subscriber.
Thus, VoIP service providers and IP network managers can avoid the costs and any applicable regulatory hassles associated with having to assign public switched telephone network (PSTN) numbers and use PSTN networks to route calls when both parties are using voice over Internet Protocol (VoIP).
For VoIP users, ENUM makes IP communications easier and ultimately less expensive. It gives subscribers control of the way that they're contacted by providing them with customized configuration of their own NAPTR, e.g., using a simple web interface. Others can contact a subscriber even when they don't know where the person is or how they want to be contacted, simply using their ENUM. With ENUM, users can dial Internet-based communications services even from numeric-only devices, including non-IP mobile and wireline phones.
ENUM technology in general helps ease the transition from circuit-switched to voice over Internet protocol (VoIP) communications. However, there are particular problems using ENUM services with respect to international callers. For example, an international caller using ENUM services in the US might dial 9-1-1. However, conventional ENUM services cannot successfully deliver a full callback phone number of the international caller to a 9-1-1 answering agency such as a public safety answering point (PSAP). This is because of restrictions caused by the North American Numbering Plan (NANP). In particular, the NANP requires use of 10-digit fields to transmit information. In this type case, an originator of communication (voice, text or video) cannot pass the required re-contact information to the end point because the international caller's number may not fit within the confines of the NANP 10-digit information field.
There is a need for a suitable method and apparatus for reliably providing callback number information for all callers from all sources within an electronic numbering (ENUM) architecture.